From patchwork Mon May 26 05:29:13 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sujit Reddy Thumma X-Patchwork-Id: 4239601 Return-Path: X-Original-To: patchwork-linux-arm-msm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id E02CE9F1E7 for ; Mon, 26 May 2014 05:29:46 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 07638201CE for ; Mon, 26 May 2014 05:29:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0C4F5201C8 for ; Mon, 26 May 2014 05:29:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751642AbaEZF3o (ORCPT ); Mon, 26 May 2014 01:29:44 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:36316 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751624AbaEZF3n (ORCPT ); Mon, 26 May 2014 01:29:43 -0400 Received: from smtp.codeaurora.org (localhost [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id 4417213ED5D; Mon, 26 May 2014 05:29:43 +0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 486) id 374FD13F35C; Mon, 26 May 2014 05:29:43 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-7.5 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from srthumm-ics.ap.qualcomm.com (unknown [202.46.23.54]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: sthumma@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id AAB3113EF07; Mon, 26 May 2014 05:29:40 +0000 (UTC) From: Sujit Reddy Thumma To: vinholikatti@gmail.com, santoshsy@gmail.com, linux-scsi@vger.kernel.org, JBottomley@parallels.com Cc: Sujit Reddy Thumma , linux-arm-msm@vger.kernel.org Subject: [RESEND PATCH V7 4/6] scsi: ufs: Fix hardware race conditions while aborting a command Date: Mon, 26 May 2014 10:59:13 +0530 Message-Id: <1401082155-23184-5-git-send-email-sthumma@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 In-Reply-To: <1401082155-23184-1-git-send-email-sthumma@codeaurora.org> References: <1401082155-23184-1-git-send-email-sthumma@codeaurora.org> X-Virus-Scanned: ClamAV using ClamSMTP Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP There is a possible race condition in the hardware when the abort command is issued to terminate the ongoing SCSI command as described below: - A bit in the door-bell register is set in the controller for a new SCSI command. - In some rare situations, before controller get a chance to issue the command to the device, the software issued an abort command. - If the device recieves abort command first then it returns success because the command itself is not present. - Now if the controller commits the command to device it will be processed. - Software thinks that command is aborted and proceed while still the device is processing it. - The software, controller and device may go out of sync because of this race condition. To avoid this, query task presence in the device before sending abort task command so that after the abort operation, the command is guaranteed to be non-existent in both controller and the device. Signed-off-by: Sujit Reddy Thumma Reviewed-by: Yaniv Gardi Tested-by: Dolev Raviv Acked-by: Vinayak Holikatti --- drivers/scsi/ufs/ufshcd.c | 70 +++++++++++++++++++++++++++++++++++++---------- 1 file changed, 55 insertions(+), 15 deletions(-) diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index c3acadc..52f66e4 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -2695,6 +2695,12 @@ static int ufshcd_host_reset(struct scsi_cmnd *cmd) * ufshcd_abort - abort a specific command * @cmd: SCSI command pointer * + * Abort the pending command in device by sending UFS_ABORT_TASK task management + * command, and in host controller by clearing the door-bell register. There can + * be race between controller sending the command to the device while abort is + * issued. To avoid that, first issue UFS_QUERY_TASK to check if the command is + * really issued and then try to abort it. + * * Returns SUCCESS/FAILED */ static int ufshcd_abort(struct scsi_cmnd *cmd) @@ -2703,7 +2709,8 @@ static int ufshcd_abort(struct scsi_cmnd *cmd) struct ufs_hba *hba; unsigned long flags; unsigned int tag; - int err; + int err = 0; + int poll_cnt; u8 resp = 0xF; struct ufshcd_lrb *lrbp; @@ -2711,33 +2718,59 @@ static int ufshcd_abort(struct scsi_cmnd *cmd) hba = shost_priv(host); tag = cmd->request->tag; - spin_lock_irqsave(host->host_lock, flags); + /* If command is already aborted/completed, return SUCCESS */ + if (!(test_bit(tag, &hba->outstanding_reqs))) + goto out; - /* check if command is still pending */ - if (!(test_bit(tag, &hba->outstanding_reqs))) { - err = FAILED; - spin_unlock_irqrestore(host->host_lock, flags); + lrbp = &hba->lrb[tag]; + for (poll_cnt = 100; poll_cnt; poll_cnt--) { + err = ufshcd_issue_tm_cmd(hba, lrbp->lun, lrbp->task_tag, + UFS_QUERY_TASK, &resp); + if (!err && resp == UPIU_TASK_MANAGEMENT_FUNC_SUCCEEDED) { + /* cmd pending in the device */ + break; + } else if (!err && resp == UPIU_TASK_MANAGEMENT_FUNC_COMPL) { + u32 reg; + + /* + * cmd not pending in the device, check if it is + * in transition. + */ + reg = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL); + if (reg & (1 << tag)) { + /* sleep for max. 200us to stabilize */ + usleep_range(100, 200); + continue; + } + /* command completed already */ + goto out; + } else { + if (!err) + err = resp; /* service response error */ + goto out; + } + } + + if (!poll_cnt) { + err = -EBUSY; goto out; } - spin_unlock_irqrestore(host->host_lock, flags); - lrbp = &hba->lrb[tag]; err = ufshcd_issue_tm_cmd(hba, lrbp->lun, lrbp->task_tag, UFS_ABORT_TASK, &resp); if (err || resp != UPIU_TASK_MANAGEMENT_FUNC_COMPL) { - err = FAILED; + if (!err) + err = resp; /* service response error */ goto out; - } else { - err = SUCCESS; } + err = ufshcd_clear_cmd(hba, tag); + if (err) + goto out; + scsi_dma_unmap(cmd); spin_lock_irqsave(host->host_lock, flags); - - /* clear the respective UTRLCLR register bit */ - ufshcd_utrl_clear(hba, tag); - __clear_bit(tag, &hba->outstanding_reqs); hba->lrb[tag].cmd = NULL; spin_unlock_irqrestore(host->host_lock, flags); @@ -2745,6 +2778,13 @@ static int ufshcd_abort(struct scsi_cmnd *cmd) clear_bit_unlock(tag, &hba->lrb_in_use); wake_up(&hba->dev_cmd.tag_wq); out: + if (!err) { + err = SUCCESS; + } else { + dev_err(hba->dev, "%s: failed with err %d\n", __func__, err); + err = FAILED; + } + return err; }